1. Field of the Invention
The present invention relates to an image-forming device, and more particularly to an image-forming device which suppresses flicker.
2. Description of the Related Art
Conventionally, to form a predetermined image, an image-forming device is utilized in which the image is exposed onto a photosensitive material and then transferred from the photosensitive material to a transfer material.
In this sort of image-forming device, the image is transferred to the transfer material by winding the transfer material onto a heated heating drum and superposing the photosensitive material with the transfer material.
At this time, for satisfactory transfer of the image onto the transfer material, temperature control is very important. Therefore, the heating drum surface is maintained at a predetermined temperature by feedback control of a heat source provided inside the heating drum; for example, a halogen lamp. Specifically, temperature control of the heating drum is performed by performing fixed period on/off control of the halogen lamp, and altering a duty ratio of the on/off control on the basis of the surface temperature of the heating drum.
In recent years, concerns have been registered about the effects of electric goods on the human body, and anti-flicker countermeasures have been called for in Europe. “Flicker” is defined as “an unsettling influence on vision brought about by photic stimulation due to time variations in intensity or spectral distribution.” In an image-forming device, flicker (as in fluorescent roomlights and the like) is brought about, for example, by voltage variations due to on/off control of a heater of a heating drum. Accordingly, measures to suppress flicker in image-forming devices are called for.